In April this year, the US auto giant, Ford, launched a novel marketing campaign. It gave 100 web-savvy drivers, across the US, it’s new Fiesta subcompact, free to be test-driven for six months. It also decided to foot their fuel expenses. All that the drivers had to do was share their adventures and views online! Did that get your attention? Then you can imagine how much potential all those videos and tweets, from the drivers, have to pull...